The new method allows processing food waste into biofuel with greater efficiency.
According to the United Nations, people send to the garbage about a third of all food. Although specific figures differ in different countries (for example, in Europe and North America, the volume of ejected products per year is about 100 kg per person, and in poor regions of Africa and Asia – 10 kg), as a result, still a huge amount of 1, 3 billion tons per year. Of course, a natural question arises whether it is impossible to do something useful with this food garbage, especially since there are so many.
One option is to make biofuel from it. The idea itself is not new, and fermentation of carbohydrates and transesterification of fats is usually used here (for interesterification, complex fat molecules exchange their structural elements, so that the fats decrease the melting temperature, they oxidize better with oxygen, etc.). However, with the help of fermentation of carbohydrates and transesterification of fats into biofuels, only a part of the garbage can be transferred.
Researchers of science and technology proposed a more effective approach to the utilization of food waste. In their experiments, they used the hydrothermal liquefaction method, which is not only significantly more energy efficient, but also allows the conversion of all raw materials into biofuel with minimal waste. In addition, the hydrothermal liquefaction method also allows biofuel production from wet biomass, excluding the drying stage of raw materials with the inevitable energy costs for this drying.
After subjecting the Parmesan cheese, ham and apples to hydrothermal liquefaction, the researchers found that the result is a water-soluble fraction and a water-insoluble oil (in the case of apples, only a water-soluble fraction was obtained). Molecular composition of the reaction products is very diverse and more like not ordinary oil, but pyrolysis products of wood (tar). Details of the results of experiments are described in an article in the European Journal of Mass Spectrometry.
In the long term, the hydrothermal liquefaction method can be optimized to produce different types of biofuels – for example, biofuels suitable for cars – but first we need to describe in more detail which molecules are produced by this method of processing food waste.
Picture Credit: Ben_Kerckx